1 00:00:00,750 --> 00:00:02,010 When working with strings. 2 00:00:02,040 --> 00:00:05,160 Another common task is to remove a prefix. 3 00:00:05,160 --> 00:00:15,440 Consider a URL with the common prefix https and we want to remove this prefix so we can focus on just 4 00:00:15,450 --> 00:00:21,270 a part of the URL that the users need to enter into an address bar. 5 00:00:21,300 --> 00:00:22,920 Here's how you do that. 6 00:00:22,950 --> 00:00:26,940 Firstly, we will enter the auxiliary URL. 7 00:00:27,300 --> 00:00:31,800 URL and here we will enter. 8 00:00:32,680 --> 00:00:44,380 Http oxley.com and is actually Udemy URL but in this case Udemy url will be https. 9 00:00:44,410 --> 00:00:44,980 Right. 10 00:00:45,010 --> 00:00:46,780 It will have different. 11 00:00:47,710 --> 00:00:48,280 Perfect. 12 00:00:50,180 --> 00:00:53,300 And here we will udemy.com. 13 00:00:54,050 --> 00:00:55,010 Now. 14 00:00:57,810 --> 00:00:59,010 Let's do this. 15 00:00:59,040 --> 00:00:59,640 Oxalate. 16 00:00:59,640 --> 00:01:02,090 That oxalate equals oxalate. 17 00:01:02,760 --> 00:01:07,590 Remove prefix http http. 18 00:01:08,880 --> 00:01:09,450 Here. 19 00:01:09,450 --> 00:01:13,710 And for Udemy we will use different https, right? 20 00:01:15,620 --> 00:01:18,080 What Udemy URL. 21 00:01:19,210 --> 00:01:21,730 Udemy url dot remove prefix. 22 00:01:21,790 --> 00:01:23,320 Http here. 23 00:01:23,350 --> 00:01:33,280 So if we do this and let's print this after that print url and print Udemy url. 24 00:01:33,280 --> 00:01:34,000 That's it. 25 00:01:34,860 --> 00:01:36,540 Now let's run this. 26 00:01:36,960 --> 00:01:38,190 And as you can see here. 27 00:01:38,190 --> 00:01:47,940 Yes, excellent Comet changed, but all udemy.com is left unchanged because we need to add s here to 28 00:01:47,940 --> 00:01:49,610 completely fix this. 29 00:01:49,620 --> 00:01:52,920 And here, as you can see here, com is changed. 30 00:01:52,920 --> 00:02:02,880 So you enter the name of the variable followed by a dot and then the method remove prefix. 31 00:02:03,210 --> 00:02:09,210 So inside the parentheses enter the prefix you want to remove from the original string. 32 00:02:10,380 --> 00:02:16,320 So like the methods for removing whitespace remove prefix leaves the original string unchanged. 33 00:02:16,350 --> 00:02:24,510 So if you want to keep the new value with the prefix removed, either reassign to the original variable 34 00:02:24,690 --> 00:02:28,230 like I did here or assign it to a new variable. 35 00:02:28,710 --> 00:02:34,920 So when you see a URL in an address bar, uh, the http. 36 00:02:36,010 --> 00:02:38,290 This part isn't shown. 37 00:02:38,320 --> 00:02:43,660 The browser is probably using a method like remove prefix. 38 00:02:44,050 --> 00:02:45,460 Behind the scenes. 39 00:02:46,490 --> 00:02:53,720 Let's actually now learn about how to avoid syntax errors with strings. 40 00:02:53,780 --> 00:03:01,400 So one kind of error that you might see with some regularity is a syntax error. 41 00:03:01,430 --> 00:03:09,260 A syntax error occurs when Python doesn't recognize a section of your program as valid python code. 42 00:03:09,290 --> 00:03:15,890 For example, if you use apostrophe within a single quotes, you will produce error. 43 00:03:15,920 --> 00:03:22,700 This happens because Python interprets everything between the first single quote and the apostrophe 44 00:03:22,730 --> 00:03:23,900 as a string. 45 00:03:23,930 --> 00:03:27,590 So it then tries to interpret the rest of. 46 00:03:29,620 --> 00:03:34,810 Uh, interpret the rest of the text as a python code, which causes errors. 47 00:03:34,810 --> 00:03:39,700 So here's how you use the single and the double quotes correctly. 48 00:03:39,850 --> 00:03:43,000 So now we will enter this here. 49 00:03:43,120 --> 00:03:46,210 Now I will share this quotes with you. 50 00:03:46,210 --> 00:03:47,050 So. 51 00:03:49,060 --> 00:03:51,070 Example one. 52 00:03:52,790 --> 00:03:53,270 Here. 53 00:03:55,060 --> 00:03:55,990 Now. 54 00:04:13,430 --> 00:04:14,360 I'll do this. 55 00:04:14,640 --> 00:04:14,900 That's. 56 00:04:16,630 --> 00:04:17,830 And now. 57 00:04:19,140 --> 00:04:19,560 Um. 58 00:04:25,970 --> 00:04:27,860 Now, let's actually write this here. 59 00:04:28,340 --> 00:04:33,110 As we said, the message here one. 60 00:04:33,950 --> 00:04:40,200 Oh, one of the one of the titans of. 61 00:04:41,600 --> 00:04:46,580 Fighters strength is its diverse. 62 00:04:53,700 --> 00:04:54,900 Yeah, it's. 63 00:04:55,080 --> 00:04:56,580 Is it? 64 00:04:58,040 --> 00:04:59,270 Diverse. 65 00:05:01,400 --> 00:05:02,300 Community. 66 00:05:03,240 --> 00:05:03,900 Here. 67 00:05:03,900 --> 00:05:05,550 We will print this message. 68 00:05:06,060 --> 00:05:06,810 Message? 69 00:05:08,610 --> 00:05:09,990 I was, actually. 70 00:05:13,320 --> 00:05:16,710 Now we will create a text file here and. 71 00:05:19,030 --> 00:05:19,690 Here. 72 00:05:19,690 --> 00:05:30,160 The first rope appears inside a set of double quotes so the python interpreter has no trouble executing 73 00:05:30,160 --> 00:05:31,720 and running this command. 74 00:05:31,720 --> 00:05:33,760 So it's okay for now. 75 00:05:34,300 --> 00:05:37,480 However, if you use single quotes. 76 00:05:38,330 --> 00:05:43,760 Python cannot identify where the string should end. 77 00:05:44,060 --> 00:05:50,300 So here we will get an error and this code will not compile because as you can see, we have an error 78 00:05:50,300 --> 00:05:51,650 in line one message. 79 00:05:51,810 --> 00:05:56,020 The python's strength is its diverse community. 80 00:05:56,030 --> 00:05:57,830 Invalid syntax. 81 00:05:59,790 --> 00:06:03,330 And here you will see this error something. 82 00:06:03,540 --> 00:06:11,130 And in the output you can see that error occurs right after the final single quote here. 83 00:06:13,690 --> 00:06:20,740 And this syntax error indicates that the interpreter doesn't recognize something in the code as valid 84 00:06:20,770 --> 00:06:21,250 python code. 85 00:06:21,280 --> 00:06:21,660 Right. 86 00:06:21,670 --> 00:06:28,780 And it thinks the problem might be a string that's not quoted correctly and the errors can. 87 00:06:29,680 --> 00:06:34,590 From a variety of sources, and I will point out some common ones as they arise. 88 00:06:34,600 --> 00:06:40,060 So you might see syntax errors often as you learn to write proper python code. 89 00:06:40,420 --> 00:06:45,160 So syntax errors are also the least specific kinds of errors. 90 00:06:45,160 --> 00:06:51,130 So they can be difficult and frustrating to identify and correct. 91 00:06:51,130 --> 00:06:59,140 So if you get stuck on a particular step or an error, you can ask me and I will answer them immediately.